This type of relay transport apparatus is coupled between an image forming apparatus, which forms images on paper sheets, and a post-processing apparatus, which performs post processing on the paper sheets on which images are formed by the image forming apparatus. This relay transport apparatus generally includes a transport path, a transport unit, and a driving unit (for example, a motor). The transport path transports paper sheets from the image forming apparatus to the post-processing apparatus. The transport unit transports the paper sheets along the transport path. The driving unit drives the transport unit. Conventional relay transport apparatuses have two types: one-motor drive system and a two-motor drive system (PATENT LITERATURE 1).
(Relay Transport Apparatus of One-Motor Drive System)
The relay transport apparatus of one-motor drive system includes one motor as a driving unit. This motor drives all transport units. Since this relay transport apparatus includes only one motor as the driving unit, advantageous in reduction in power consumption. However, with this relay transport apparatus of one-motor drive system, since the one motor drives all the transport units, there is a drawback that transport speeds of a plurality of respective transport units cannot be individually changed.
Due to this drawback, for example, in the case where the transport speed is accelerated in the relay transport apparatus and paper sheets (in particular, paper sheets whose length in a transport direction is equal to or more than a predetermined reference length) are transported, the following drawback is present. That is, to increase the transport speed in the relay transport apparatus, the transport speeds of all the transport units need to be increased. However, to carry in the subsequent paper sheet from the image forming apparatus to the relay transport apparatus, the transport speed in the relay transport apparatus needs to be decelerated to match the transport speed at the image forming apparatus side.
Accordingly, to carry in the subsequent paper sheet from the image forming apparatus to the relay transport apparatus, it is necessary to waited for the paper sheet during transport completely to pass though the relay transport apparatus and then decelerate the transport speed in the relay transport apparatus. Subsequently, the subsequent paper sheet needs to be carried in from the image forming apparatus to the relay transport apparatus. Therefore, there is a drawback of long paper interval.
(Relay Transport Apparatus of Two-Motor Drive System)
Meanwhile, the relay transport apparatus of two-motor drive system includes two motors as the driving units. These respective motors drive a plurality of transport units. The plurality of transport units correspond to any one of the respective motors and are driven by the corresponding motors. For example, the transport path of the relay transport apparatus is divided into two. One motor drives the respective transport units in one section (for example, an upstream side). The other motor drives the respective transport units in the other section (for example, a downstream side).
This relay transport apparatus of two-motor drive system has two motors as the driving units. Accordingly, individually driving the respective motors allows changing the transport speeds of the plurality of transport units individually by the respective corresponding motors.
Accordingly, when the paper sheet passes through the segment at the upstream side of the transport path in the relay transport apparatus, only the transport speed of the respective transport units in the segment at the upstream side can be decelerated. That is, when the subsequent paper sheet is carried in from the image forming apparatus to the relay transport apparatus, it is not necessary to wait until the paper sheet during transport completely passes through the relay transport apparatus. This is advantageous in that the paper sheets can be transported at shorten paper interval. However, the relay transport apparatus of two-motor drive system uses two motors; therefore, there is a drawback of large power consumption.